Fluid contactor-diffuser tray assembly

ABSTRACT

A separations tray assembly for use in a fluid-fluid exchange column. The separations tray assembly is of the type where a first fluid, in a continuous phase, is directed across successive trays in a serpentine flow path. A second fluid, in a dispersed phase ascends through apertures in the tray thus inducing interaction and mass transfer with the first fluid. In accordance with one aspect of the present invention, the separations tray further includes a diffuser skirt, having apertures disposed therein, operatively coupled to a fluid channel. The diffuser skirt is operable to direct the first fluid to cover substantially an entire volumetric cross-flow window between successive separations trays and to induce stirring and mixing of the first fluid and the second fluid to effect efficient mass transfer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority from and incorporates by referencethe entire disclosure of U.S. Provisional Patent Application No.61/345,439, filed May 17, 2010. Additionally, the present applicationincorporates by reference the entire disclosure of U.S. patentapplication Ser. No. 12/408,333, filed Mar. 20, 2009, U.S. patentapplication Ser. No. 12/109,781, filed Apr. 25, 2008, and U.S.Provisional Patent Application No. 61/178,676, filed May 15, 2009.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to mass-transfer trays for chemicalprocess columns and, more particularly, but not by way of limitation, toan improved liquid-liquid contactor tray for facilitating increased masstransfer efficiency.

2. History of Related Art

Distillation columns have been developed and used for many decades toseparate selected components from a multicomponent stream. The major“separations” process is commonly known in the art as “fractionation.”Successful fractionation in a distillation column depends upon intimatecontact between a heavier fluid and a lighter fluid. Some contactdevices, such as, for example, trays, are characterized by relativelyhigh pressure drop and relatively high fluid hold-up. One type ofcontact apparatus utilizes fluid in a vapor phase to contact fluid in aliquid phase. Another type of contact apparatus is structured packing.Structured packing is energy efficient as it exhibits low pressure dropand low fluid hold-up. However, these very properties at times makecolumns equipped with structured packing difficult to operate in astable, consistent manner. Moreover, many applications simply requirethe use of trays.

A particularly effective tray in process columns is a sieve tray.Typically, the sieve tray is constructed with a plurality of aperturesformed in a deck surface. The plurality of apertures permit ascendinglighter fluid to flow into direct engagement with heavier fluid that isflowing across the sieve tray. When there is sufficient lighter-fluidflow upwardly through the sieve tray, the heavier fluid is preventedfrom running downwardly through the plurality of apertures (referred toas “weeping”). A small degree of weeping is normal in sieve trays whilea larger degree of weeping is detrimental to the capacity and efficiencyof the tray. Such trays may be either single-pass or multi-pass. Inaddition, such trays may incorporate serpentine flow, orbital flow, oruni-directional flow.

Another type of “separations” process involves mass transfer between twofluids which are both in a liquid state. This is commonly referred to as“fluid-fluid exchange.” The primary advantage of fluid-fluid exchangeover fluid-vapor exchange is an amount of process energy required. Inthe fluid-vapor exchange, substantial energy must be provided andconsumed to boil a fluid into a vapor state and maintain the fluid inthe vapor state for the duration of the process. In contrast, mostfluid-fluid exchange processes operate at temperatures slightly aboveambient temperature such as, for example, 90° F. resulting insignificant energy savings.

In cases involving fluid-fluid exchange, there are specific performanceissues that impact efficiency. In typical fluid-fluid exchange columns,a first fluid is in a continuous phase and a second fluid is in adispersed phase. In one arrangement, the heavier fluid, in a continuousphase, is passed downwardly in a circuitous path across a series ofhorizontally disposed trays spaced in a vertical relationship, one tothe other. The heavier fluid forms a fluid layer on the trays. Dropletsof the lighter fluid, in a dispersed phase, ascend through the pluralityof apertures and interact with the continuous fluid. This arrangementmay be used, for example, in re-capture of an acid where the heavierfluid is water containing the acid and the lighter fluid is a selectedsolvent. In another arrangement, the heavier fluid is the dispersedphase and the lighter fluid is the continuous phase. In thisarrangement, the heavier fluid forms droplets which fall downwardlythrough the plurality of apertures. The heavier fluid droplets fallthrough the lighter fluid, in continuous phase, flowing upwardly in acircuitous path across an underside of the trays. This arrangement maybe used, for example in solvent recovery of Benzene from aromaticsprocess streams.

In conventional fluid-fluid contactor trays, velocities of thecontinuous-phase fluid are very low relative to fluid-vapor columns. Thelow velocities in the continuous-phase fluid result in thecontinuous-phase fluid having minimal head pressure thereby inducingre-circulation and stagnation. Recirculation and stagnation reducesmass-transfer driving force. Tray areas where no mass transfer betweenthe continuous-phase fluid and the dispersed-phase fluid occurs arereferred to as “dead zones.” Dead zones form in locations where thecontinuous-phase fluid stagnates thus exhausting the solvent absorptioncapability. Furthermore, the low velocities of the continuous-phasefluid result in the continuous-phase fluid tending to not cover anentire surface of a tray. Such incomplete tray coverage lessens an areaof effective mass transfer and reduces an efficiency of the tray. Theseproblems are generally present regardless of whether the heavier fluidor the lighter fluid is used as the continuous phase.

U.S. Pat. No. 7,556,734, assigned to AMT International Inc., teaches anexchange column for contacting liquid in a continuous phase with liquidin a dispersed phase. Contact between liquid in the continuous phase andliquid in the dispersed phase is enhanced by providing upstandingbaffles on lower trays interspersed with depending baffles from traysabove. In addition, flow distribution partitions extend along a flowpath, between the baffles, to distribute liquid flow across the trays.

U.S. Pat. No. 4,247,521, assigned to Union Carbide Corporation, teachesa liquid-liquid contacting tray having a channelized liquid transfermeans for transferring continuous phase liquid from a contacting zone onone side of the tray to a contacting zone on the other side of the tray.The channelized liquid transfer means includes a settling sectionoperable to allow disengagement of the discontinuous phase liquid fromthe continuous phase liquid, and a pressure drop section.

U.S. Pat. No. 2,752,229 assigned to Universal Oil Products Company,teaches a tower for effecting countercurrent contacting of fluidstreams, particularly liquid-liquid contacting. The tower includes aplurality of vertically spaced perforated liquid distributing decksextending across a confined chamber. Sloping liquid downpipe assembliesextend from a liquid receiving well on one deck to a liquid sealreservoir of the next lower deck. Use of the sloping downpipe ensuresthat the continuous-phase liquid moves in the same direction acrosssuccessive trays thus creating a uni-directional flow path.

SUMMARY OF THE INVENTION

The present invention relates to a separations tray assembly for use ina fluid-fluid exchange column. The separations tray assembly is of thetype where a first fluid, in a continuous phase, is directed across thetray in a cross-flow path. A second fluid, in a dispersed phase, ascendsthrough apertures in the tray thus inducing interaction and masstransfer with the first fluid. In accordance with one aspect of thepresent invention, the separations tray further includes a diffuserskirt, having apertures disposed therein, operatively coupled to a fluidchannel. The diffuser skirt is operable to direct the first fluid tocover substantially an entire surface of the separations tray and toinduce stirring and mixing of the first fluid and the second fluid toeffect efficient mass transfer.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the method and system of the presentinvention may be obtained by reference to the following DetailedDescription when taken in conjunction with the accompanying drawingswherein:

FIG. 1 is a side-elevational cross-sectional view of a prior artfluid-fluid exchange column;

FIG. 2 is a side-elevational cross-sectional view of a prior-artfluid-fluid exchange column;

FIG. 3 is a diagrammatic, side-elevational, cross-sectional view of afluid-fluid exchange column according to an exemplary embodiment;

FIG. 4 is a top-plan, diagrammatic view of a tray according to anexemplary embodiment;

FIG. 5 is a diagrammatic, side-elevational, cross-sectional view of afluid-fluid exchange column according to an exemplary embodiment;

FIG. 6 is a top-plan, diagrammatic view of a tray according to anexemplary embodiment;

FIG. 7A is a perspective view of a diffuser skirt according to anexemplary embodiment;

FIGS. 7B-7E are top-plan views of diffuser skirts according to exemplaryembodiments;

FIG. 7F is a top-plan, diagrammatic view of a tray according to anexemplary embodiment;

FIG. 8 is a diagrammatic, side-elevational, cross-sectional view of afluid-fluid exchange column according to an exemplary embodiment;

FIG. 9A is a top-plan, diagrammatic view of a tray according to anexemplary embodiment;

FIG. 9B is a top-plan, diagrammatic view of a tray according to anexemplary embodiment; and

FIG. 10 is a is a diagrammatic, side-elevational, cross-sectional viewof a fluid-fluid exchange column according to an exemplary embodiment.

DETAILED DESCRIPTION

Various embodiments of the present invention will now be described morefully with reference to the accompanying drawings. The invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein; rather, the embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart.

Referring now to FIG. 1, there is shown a side-elevationalcross-sectional view of a prior-art fluid-fluid exchange column. Afluid-fluid exchange column 10 includes a continuous-fluid-feeder line12 and a first draw-off line 14. Also included are a dispersed-fluidfeeder line 16 and a second draw-off line 18. A plurality of trays20(1)-20(7) are disposed within the fluid-fluid exchange column 10.Typically, the fluid-fluid exchange column 10 is used in extractionprocesses such as, for example, extraction of an acid from water using asolvent.

Still referring to FIG. 1, the plurality of trays 20(1)-20(7) generallycomprise a solid tray or deck having a plurality of apertures 22disposed therein. The plurality of apertures 22 may include, forexample, holes, slots, floating valves, or any other appropriate type ofaperture. Separation trays such as, for example, the plurality of trays20(1)-20(7) comprise at least one of cross-flow trays with downcomersand counter-flow trays without downcomers. In cross-flow trays, alighter fluid 30 ascends through the plurality of apertures 22 andcontacts a heavier fluid 24 moving across the plurality of trays20(1)-20(7). In an active area, the heavier fluid 24 and the lighterfluid 30 mix and fractionation occurs. In counter-flow trays, both thelighter fluid 30 and the heavier fluid 24 pass through the plurality ofapertures 22.

Still Referring to FIG. 1, in cross-flow operation, the heavier fluid24, in a continuous phase, is introduced to, and substantially fills,the fluid-fluid exchange column 10 via the continuous-fluid-feeder line12. The heavier fluid 24 is directed onto one of the plurality of trays20(1)-20(7) such as, for example, the tray 20(2) by means of a fluidchannel 26 from the tray 20(1) above. The fluid channel 26 is referredto as a “downcomer.” The heavier fluid 24 moves across the tray 20(1)and enters the fluid channel 26 through a downcomer entrance 28(a) andthen leaves through a downcomer exit 28(b). At the same time, thelighter fluid 30 in a dispersed phase is introduced to the fluid-fluidexchange column 10 via the dispersed-fluid feeder line 16. The lighterfluid 30 forms bubbles that rise through the heavier fluid 24.Typically, the bubbles of the lighter fluid 30 are approximately ¼ of aninch or smaller. The lighter fluid 30 rises through the fluid-fluidexchange column 10 and forms a coalesced layer on an underside of eachof the plurality of trays 20(1)-20(7). The plurality of apertures 22facilitate passage of the lighter fluid 30 through each of the pluralityof trays 20(1)-20(7) allowing interaction with the heavier fluid 24.Remaining heavier fluid 24 is removed from the fluid-fluid exchangecolumn 10 via the first draw-off line 14. Likewise, remaining lighterfluid 30 is removed from the fluid-fluid exchange column 10 via thesecond draw-off line 18.

For example, in the case of an extraction column, heavier fluid 24 suchas, for example, water containing acetic acid is pumped into thefluid-fluid exchange column 10 in a continuous phase, viacontinuous-fluid feeder-line 12. The heavier fluid 24 comprising thewater-acid mixture descends through the fluid-fluid exchange column 10in a circuitous route passing over each of the plurality of trays20(1)-20(7) in alternating directions. Simultaneously, lighter fluid 30such as, for example, a solvent containing an alkyl acetate isintroduced via the dispersed-fluid feeder line 16. The lighter fluid 30comprising the solvent-alkyl acetate mixture bubbles up through thewater-acid mixture and coalesces on the underside of each of theplurality of trays 20(1)-20(7). The solvent interacts with thewater-acid mixture and gradually absorbs the acetic acid. Thus, theconcentration of acetic acid is greatest in water-acid mixture movingacross the tray 20(1). The concentration of acetic acid in the waterdecreases as the water-acid mixture moves across each successive tray ofthe plurality of trays 20(1)-20(7) until, finally, residual water (alsoreferred to as “raffinate”) is removed from the fluid-fluid exchangecolumn 10 via the first draw-off line 14. In similar fashion, theconcentration of acetic acid in the solvent increases with eachsuccessive tray until acetic acid extract is removed from thefluid-fluid exchange column 10 via the second draw-off line 18.

Referring now to FIG. 2, there is shown a side-elevationalcross-sectional view of a prior-art fluid-fluid exchange column. Afluid-fluid exchange column 32 includes a continuous-fluid-feeder line34 and a first draw-off line 36. Also included are a dispersed-fluidfeeder line 38 and a second draw-off-line 40. A plurality of trays42(1)-42(7) are disposed within the fluid-fluid exchange column 32. Afluid-fluid exchange column such as, for example, the fluid-fluidexchange column 32 may be used in a process such as, for example,extraction of benzene from water.

Still referring to FIG. 2, the plurality of trays 42(1)-42(7) generallycomprise a solid tray or deck having a plurality of apertures 44disposed therein. The plurality of apertures 44 may include, forexample, holes, slots, floating valves, and other appropriate types ofapertures. In operation, a lighter fluid 46, in a continuous phase, isintroduced to, and substantially fills, the fluid-fluid exchange column32 via the continuous-fluid-feeder line 34. The lighter fluid 46 isdirected onto a tray such as, for example, the tray 42(6) by means of afluid channel 48 from the 42(7) tray below. The fluid channel 48 isreferred to as an “upcomer.” The lighter fluid 46 moves across the tray42(7) and enters an upcomer entrance 50(a). The lighter fluid 46 thenexits the fluid channel 48 via an upcomer exit 50(b). A heavier fluid52, in a dispersed phase, is simultaneously introduced to thefluid-fluid exchange column 32 via the dispersed-fluid feeder line 38.The heavier fluid 52 forms bubbles that descend through the lighterfluid 46. Typically, the bubbles of the heavier fluid 52 areapproximately ¼ of an inch or smaller. The heavier fluid 52 descendsthrough the fluid-fluid exchange column 32 and forms a coalesced layeron a top surface of each of the plurality of trays 42(1)-42(7). Theplurality of apertures 44 facilitate passage of the heavier fluid 52through each of the plurality of trays 42(1)-42(7) allowing interactionwith the lighter fluid 46. Residual lighter fluid 46 is removed from thefluid-fluid exchange column 32 via the first draw-off line 36. Likewise,residual heavier fluid 52 is removed from the fluid-fluid exchangecolumn 32 via the second draw-off line 40.

FIG. 2 is included herein to demonstrate that either a heavier fluid ora lighter fluid may be used in operation as the continuous phase withappropriate modifications to a structure of the fluid-fluid exchangecolumn. For ease and clarity of discussion, the following exemplaryembodiments will be described by way of example as having a heavierfluid in the continuous phase. However, one skilled in the art willrecognize that, alternatively, each of the embodiments below couldfunction with a lighter fluid as the continuous phase and flowredirected in accordance therewith.

Referring now to FIG. 3, there is shown a diagrammatic,side-elevational, cross-sectional view of a fluid-fluid exchange columnaccording to an exemplary embodiment In various embodiments, afluid-fluid exchange column 300 includes a plurality of trays302(1)-302(5) and a plurality of fluid channels 304. In variousembodiments, the plurality of fluid channels 304 may include, forexample, a downcomer or an upcomer as described hereinabove. In atypical embodiment, a tray such as, for example, the tray 302(2), allowsfluid to enter and exit via the fluid channels 304. In a typicalembodiment, the fluid channels 304 include a plurality of orificeconstrictions 306(a)-306(c) disposed therein. The plurality of orificeconstrictions 306(a)-306(c) may utilize a variety of pressure-dropcontrol devices such as, for example, an envelope-pipe reducer 306(a), aperforated plate 306(b), a plurality of baffles 306(c), and the like. Ina typical embodiment, plurality of the orifice constrictions306(a)-306(c) restrict the flow of fluid moving through the fluidchannels 304 and prevent backflow of either a continuous-phase fluid 308or a dispersed-phase fluid 310 therethrough. In a typical embodiment,the plurality of trays 302(1)-302(5) include a diffuser skirt 312(a).The diffuser skirt 312(a) includes a diffuser body and plurality ofapertures 314 therein. The diffuser skirt 312(a) depends from anunderside of the fluid channel 304. As shown by way of example in FIG.3, the diffuser skirt 312(a) extends entirely between two trays such as,for example, the trays 302(1) and the tray 302(2); however, one skilledin the art will recognize that the diffuser skirt 312(a) may not extendentirely between the two trays 302(1) and 302(2) leaving a clearancespace. Although the plurality of apertures 314 are shown by way ofexample in FIG. 3 as perforations, one skilled in the art will recognizethat, in alternative embodiments, the plurality of apertures 314 mayinclude slots, louvers, and the like. The plurality of apertures 314 areillustrated by way of example in FIG. 3 as being evenly spaced aroundthe diffuser skirt 312(a); however, the plurality of apertures 314 mayalternatively be grouped to direct the continuous-phase fluid 308 in adesired direction. By way of example, the fluid-fluid exchange column300 is shown in FIG. 3 as containing five trays 302(1)-302(5); however,one skilled in the art will recognize that, in alternative embodiments,any number of trays may be utilized.

Referring still to FIG. 3, in various embodiments, the fluid-fluidexchange column 300 includes a first conduit 312(b). In a typicalembodiment, the first conduit 312(b) includes a plurality of apertures315 disposed therein. In various embodiments, the first conduit 312(b)depends from an underside of the fluid channel 304. As shown by way ofexample in FIG. 3, the first conduit 312(b) does not extend entirelybetween two trays such as, for example, the tray 302(3) and the tray302(4); however, one skilled in the art will recognize that, inalternative embodiments, the first conduit 312(b) may extend entirelybetween the two trays 302(3) and 302(4). Although, the plurality ofapertures 315 are shown by way of example in FIG. 3 as perforations; oneskilled in the art will recognize that, in alternative embodiments, theplurality of apertures 315 may include slots, louvers, or the like. Theplurality of apertures 315 are illustrated by way of example in FIG. 3as being evenly spaced around the first conduit 312(b); however, theplurality of apertures 315 may alternatively be grouped to direct thecontinuous-phase fluid 308 in a desired direction.

Referring still to FIG. 3, in certain embodiments, the plurality ofapertures 315 are disposed on both an interior face and an exterior faceof a second conduit 312(c). Such an arrangement facilitates mixing ofthe continuous-phase fluid 308 and the dispersed-phase fluid 310 on theexterior side of the second conduit 312(c). Additionally, thisarrangement allows an active area, where mixing of the continuous-phasefluid 308 and the dispersed-phase fluid 310 occurs, to extend entirelyto the outer wall 301 of the fluid-fluid exchange column 300.

Referring still to FIG. 3, in certain embodiments, a coalescing element316 may be included on any of the plurality of trays 302(1)-302(5) tofacilitate coalescing of the dispersed-phase fluid 310. Although thecoalescing element 316 is shown in FIG. 3 as being disposed on anunderside of the plurality of trays 302(1)-302(2), one skilled in theart will recognize that the, in alternative embodiments, coalescingelement 316 may be located on a top surface of the plurality of trays302(1)-302(2) in cases where the dispersed-phase fluid 310 is heavierthan the continuous-phase fluid 308.

Still referring to FIG. 3, during operation, the continuous-phase fluid308 moves across a tray such as, for example, the tray 302(1), into thefluid channel 304, and through at least one of the plurality of orificeconstrictions 306(a)-306(c). As the continuous-phase fluid 308 movesthrough at least one of the plurality of orifice constrictions306(a)-306(c), flow of the continuous-phase fluid 308 is restrictedresulting in increased velocity of the continuous-phase fluid 308. Theadded velocity further facilitates stirring and mixing of thecontinuous-phase fluid 308 and the dispersed-phase fluid 310 forcing thecontinuous-phase fluid 308 to be spread entirely across a cross-flowvolumetric window between successive trays such as, for example, thetrays 302(1) and 302(2) preventing stagnation and reducing recirculation(also referred to as “eddy current”) in the continuous-phase fluid 308.Additionally, according to an exemplary embodiment, thrust tabs (notexplicitly shown in FIG. 3) may be incorporated in conjunction with theplurality of apertures 314 or 315 to direct the continuous-phase fluid308 to cover the entire volumetric cross-flow window between each of theplurality of trays 302(1)-302(5).

Referring now to FIG. 4, there is shown a top-plane, diagrammatic viewof a tray according to an exemplary embodiment. In a typical embodiment,a tray such as, for example, the tray 302(2) includes a diffuser skirt312(a), a plurality of baffles 408, and a plurality of vanes 412. In atypical embodiment, the diffuser skirt 312(a) forms a chord across asurface of a tray such as, for example, the tray 302(2). As illustratedin FIG. 4, a plurality of tabs 404 may be incorporated with theplurality of apertures 314 (shown in FIG. 3) to direct thecontinuous-phase fluid 308 in a desired direction thus further inducingthe continuous-phase fluid 308 to cover the entire volumetric cross-flowwindow of a tray such as, for example, the tray 302(2). The plurality ofbaffles 408 may be incorporated within the fluid channel 304 to directthe continuous-phase fluid 308 to cover the entire volumetric cross-flowwindow of a tray such as, for example, the tray 302(2). Additionally,the plurality of vanes 412 may be incorporated to impart additionalvelocity to the continuous-phase fluid 308 and to further direct thecontinuous-phase fluid 308 to cover the entire volumetric cross-flowwindow of a tray such as, for example, the tray 302(2).

Referring now to FIG. 5, there is shown a diagrammatic,side-elevational, cross-sectional view of a fluid-fluid exchange columnaccording to an exemplary embodiment. In a typical embodiment, afluid-fluid exchange column 500 includes a plurality of trays502(1)-502(5). By way of example, the fluid-fluid exchange column 500 isillustrated in FIG. 5 as having five trays 502(1)-502(5); however, oneskilled in the art will recognize that, in alternative embodiments, anynumber of trays could be utilized. In a typical embodiment, a tray suchas, for example, the tray 502(2) allows fluid to enter and exit viafluid channels 504. In various embodiments, the plurality of fluidchannels 504 may include, for example, a downcomer or an upcomer asdescribed hereinabove. In various embodiments, the fluid channels 504include at least one of the plurality of orifice constrictions306(a)-306(c) (shown in FIG. 3) disposed therein. The plurality oforifice constrictions 306(a)-306(c) are described above with respect toFIG. 3. In a typical embodiment, a plurality of diffuser skirts506(a)-506(c), each having a diffuser body and a plurality of apertures508 disposed therein, depends from an underside of the fluid channels504. As shown by way of example in FIG. 5, the plurality of diffuserskirts 506(a)-506(c) extends substantially between two trays such as,for example, the tray 502(1) and the tray 502(2); however, one skilledin the art will recognize that, in alternative embodiments, theplurality of diffuser skirts 506(a)-506(c) may not extend entirely to,for example, the tray 502(2) leaving a clearance space between theplurality of diffuser skirts 506(a)-506(c) and the tray 502(2) foradditional flow.

Still Referring to FIG. 5, in contrast to FIG. 3, the plurality ofdiffuser skirts 506(a)-506(c) are, in a typical embodiment, angledtowards an outer wall 510 of the fluid-fluid exchange column 500 therebyinducing turbulence in the continuous-phase fluid 308. Although, theplurality of apertures 508 are shown by way of example in FIG. 5 asperforations; one skilled in the art will recognize that the pluralityof apertures 508 could include slots, louvers, and other configurations.The plurality of apertures 508 are illustrated by way of example in FIG.5 as being evenly spaced around the plurality of diffuser skirts506(a)-506(c); however, the plurality of apertures 508 may alternativelybe grouped to create a specific fluid flow Additionally, in variousembodiments, at least one of inlet weirs 512(a)-512(c) may be disposedon a top surface of a tray such as, for example, the trays 502(2)-20(4)medially of the plurality of diffuser skirts 506(a)-506(c). In someembodiments, a diffuser skirt such as, for example, the plurality ofdiffuser skirts 506(b) may extend entirely to the outer wall 510 of thefluid-fluid exchange column 500. In this arrangement, the plurality ofdiffuser skirts 506(b) also performs the function of at least one of theorifice constrictions 306(a)-306(c). Such an arrangement also allows anactive area associated with a tray such as, for example, the tray 502(4)to extend entirely to the outer wall 510 of the fluid-fluid exchangecolumn 500. In addition, in some embodiments, a diffuser skirt 506(c)may seal upon a floor of an adjacent tray such as, for example, the tray502(5).

Still Referring to FIG. 5, in certain embodiments, the coalescingelement 316 may be included on any of the plurality of trays502(1)-502(5) to facilitate coalescing of the dispersed-phase fluid 310.Although the coalescing element 316 is shown in FIG. 5 as being disposedon an underside of a tray such as, for example, the trays 502(1)-502(2),one skilled in the art will recognize that, in alternative embodiments,the coalescing element 316 could be located on a top surface of a traysuch as, for example, the trays 502(1)-502(2) in those flowconfigurations where the dispersed-phase fluid 310 is heavier than thecontinuous-phase fluid 308 and the flow is redirected in accordancetherewith.

Still referring to FIG. 5, during operation, the continuous-phase fluid308 moves across a tray such as, for example, the tray 502(1), into thefluid channel 504, and through at least one of the plurality of orificeconstrictions 306(a)-306(c). As the continuous-phase fluid 308 movesthrough the plurality of diffuser skirts 506(a)-506(c). In a typicalembodiment, the diffuser skirts 506(a)-506(c) are angled towards anouter wall 510 of the fluid-fluid exchange column 500. In a typicalembodiment, flow restriction imposed by the plurality of apertures 508results in additional velocity being imparted to the continuous-phasefluid 308. The added velocity further facilitates stirring and mixing ofthe continuous-phase fluid 308 and the dispersed-phase fluid 310. Suchadded velocity also forces the continuous-phase fluid 308 to be spreadentirely across a volumetric cross-flow window between successive trayssuch as, for example, the trays 502(1)-502(2) thus preventing stagnationand reducing recirculation of the continuous-phase fluid 308. Inaddition, the continuous-phase fluid 308 passes through the plurality ofapertures 508 at right angles to the plurality of diffuser skirts506(a)-506(c). In various embodiments, some of the continuous-phasefluid 308 will pass over, for example, a solid inlet weir 512(a). In analternative embodiments, some of the continuous-phase fluid 308 couldpass through a perforated inlet weir 512(b). The interaction of theplurality of diffuser skirts 506(a)-506(c) and the perforated inlet weir512(b) introduce turbulence to the continuous-phase fluid 308. Thedirectional turbulence causes stirring of the continuous-phase fluid 308thus facilitating interaction with the dispersed-phase fluid 310.Additionally, thrust tabs (not explicitly shown in FIG. 5) may beincorporated in conjunction with the plurality of apertures 508 of theplurality of diffuser skirts 506(a)-506(c) or the perforated inlet weir512(b) to direct the continuous-phase fluid 308 to cover an entirevolumetric cross-flow window of the plurality of trays 502(1)-502(5).

Referring now to FIG. 6, there is shown a top-plane, diagrammatic viewof a tray according to an exemplary embodiment. In a typical embodimenta tray such as, for example, the tray 502(2) includes a diffuser skirt506(a) and a plurality of vanes 602. The diffuser skirt 506(a) forms achord across a surface of the tray 502(2). As illustrated in FIG. 6,thrust tabs (not explicitly shown in FIG. 6) may be incorporated withthe plurality of apertures 508 to direct to the continuous-phase fluid308 (not shown in FIG. 6) in a desired direction thereby inducing thecontinuous-phase fluid 308 to cover an entire volumetric cross-flowwindow of a tray such as, for example the tray 502(2). Additionally, atleast one or a plurality of vanes 602 may be disposed on a tray such as,for example, the tray 502(2) to impart additional velocity to thecontinuous-phase fluid 308 and to further direct the continuous-phasefluid 308 to cover the entire volumetric cross-flow window of a traysuch as, for example, the tray 502(2). According to exemplaryembodiments, the vanes 602 may be curved, angled, or straight to reduceeddy currents in the continuous-phase fluid 308 and the dispersed-phasefluid 310 (not shown in FIG. 6). Reducing eddy currents preventsrecirculation of either the continuous-phase fluid 308 or thedispersed-phase fluid 310 and improves efficiency of the plurality oftrays 502(1)-502(5). The plurality of apertures 508 are illustrated byway of example in FIG. 6 as being evenly spaced around the diffuserskirt 506(a)-506(c); however, the plurality of apertures 508 mayalternatively be grouped to create a specific fluid flow.

Referring now to FIG. 7A, there is shown a perspective view of adiffuser skirt according to an exemplary embodiment. In a typicalembodiment, a diffuser skirt 700 comprises a plurality of apertures 702.The plurality of apertures 702 are illustrated by way of example in FIG.7A as being evenly spaced around the diffuser skirt 700; however, theplurality of apertures 702 may, in alternative embodiments, be groupedto create a specific fluid flow. In a typical embodiment the diffuserskirt 700 is substantially convex shaped. The diffuser skirt 700 may be,for example, roughly infundibular or quasi-frustoconical in shape.

FIGS. 7B-7E illustrate various exemplary shapes of the diffuser skirt700. FIG. 7B illustrates the diffuser skirt 700 as chevron shaped. FIG.7C illustrates the diffuser skirt 700 as pentagon-shaped, FIG. 7Dillustrates the diffuser skirt 700 as open hexagon-shaped. FIG. 7Eillustrates the diffuser skirt 700 as an open polygon or any otherappropriate shape.

Referring specifically to FIG. 7F, there is shown a top-plane,diagrammatic view of a tray according to an exemplary embodiment. In atypical embodiment, a tray 704 includes a diffuser skirt 700 having aplurality of apertures 702 therein. In a typical embodiment, thediffuser skirt 700 is substantially arc-shaped. In a typical embodiment,the diffuser skirt 700 may be, for example, roughly infundibular orquasi-frustoconical in shape. During operation, the continuous-phasefluid 308 moves through the plurality of apertures 702 at an approximateright angle to the diffuser skirt 700. The roughly arcuate profile ofthe diffuser skirt 700 facilitates directing the continuous-phase fluid308 over the entire volumetric cross-flow window between successivetrays such as, for example, the tray 704. In various embodiments, tabs64 (shown in FIG. 4) may be incorporated with the plurality of apertures702 to direct the continuous-phase fluid 308 in a desired directionthereby inducing the continuous-phase fluid 308 to cover the entirevolumetric cross-flow window between the successive trays such as, forexample, the trays 502(1)-502(2) (shown in FIG. 5). Additionally, atleast one or a plurality of vanes 706 may be incorporated to impartadditional velocity to the continuous-phase fluid 308 and to furtherdirect the continuous-phase fluid 308 to cover the entire volumetriccross-flow window of a tray such as, for example, the tray 704. Thevanes 706 may be curved, angled, or straight to reduce eddy currents inthe continuous-phase fluid 308 and the dispersed-phase fluid 310 (notexplicitly shown in FIG. 7). The plurality of apertures 702 areillustrated by way of example in FIG. 7F as being evenly spaced aroundthe diffuser skirt 700; however, the plurality of apertures 702 may, inalternative embodiments, be grouped to direct the continuous-phase fluid308 to cover an entire volumetric cross-flow window of the tray 704.

Referring now to FIG. 8, there is shown a diagrammatic,side-elevational, cross-sectional view of a fluid-fluid exchange columnaccording to an exemplary embodiment. A fluid-fluid exchange column 800includes a plurality of trays 802(1)-802(4). In a typical embodiment, atray such as, for example, the tray 802(2) allows fluid to enter andexit via fluid channels 804. In various embodiments, the plurality offluid channels 804 may include, for example, a downcomer or an upcomeras described hereinabove. In a various embodiments, the fluid channels804 include at least one of the plurality of orifice constrictions306(a)-306(c) (shown in FIG. 3) discussed above with respect to FIG. 3disposed therein. A downspout 806, having a plurality of apertures 808therein, depends from an underside of the fluid channel 804. As shown byway of example in FIG. 8, the downspout 806 extends substantiallybetween two successive trays such as, for example, the tray 802(1) andthe tray 802(2) leaving a clearance gap 810 between the downspout 806and the tray 802(2); however, one skilled in the art will recognizethat, in alternative embodiments, the downspout 806 may extend entirelyto the tray 802(2) leaving no clearance space. Although, the pluralityof apertures 808 are shown by way of example in FIG. 8 as perforations;one skilled in the art will recognize that, in alternative embodiments,the plurality of apertures 808 could include slots, louvers, or thelike. The plurality of apertures 808 are illustrated by way of examplein FIG. 8 as being evenly spaced around the downspout 806; however, theplurality of apertures 808 may alternatively be grouped to create aspecific fluid flow. By way of example, the fluid-fluid exchange column800 is illustrated as including four trays 802(1)-802(4); however, oneskilled in the art will recognize that, in alternative embodiments, anynumber of trays could be utilized.

Still Referring to FIG. 8, in certain embodiments, the coalescingelement 316 may be included on the any of the plurality of trays802(1)-802(4) to facilitate coalescing of the dispersed-phase fluid 310.Although the coalescing element 316 is shown in FIG. 8 as being disposedon an underside of the plurality of trays 802(1)-802(4), one skilled inthe art will recognize that, in alternative embodiments, the coalescingelement 316 could be located on a top surface of the plurality of trays802(1)-802(4) in cases where the dispersed-phase fluid 310 is heavierthan the continuous-phase fluid 308.

Still referring to FIG. 8, during operation, a continuous-phase fluid308 moves across a tray such as, for example, the tray 802(1), into thefluid channel 804, and through at least one of the orifice constrictions306(a)-306(c). As the continuous-phase fluid 308 moves through thedownspout 806, the flow restriction imposed by the plurality ofapertures 808 results in velocity being imparted to the continuous-phasefluid 308. The added velocity also facilitates stirring and mixing ofthe continuous-phase fluid 308 and the dispersed-phase fluid 310. Suchadded velocity also forces the continuous-phase fluid 308 to bedispersed across an entire volumetric cross-flow window betweensuccessive trays such as, for example, the tray 802(1) and the tray802(2) thus preventing stagnation and recirculation. Additionally,thrust tabs (not explicitly shown in FIG. 8) may be incorporated inconjunction with the plurality of apertures 808 to direct thecontinuous-phase fluid 308 to cover the entire volumetric cross-flowwindow of the plurality of trays 802(1)-802(4).

Referring now to FIGS. 9A and 9B, there is shown a top-plane,diagrammatic view of a tray according to an exemplary embodiment. In atypical embodiment a tray such as, for example, the tray 802(2) includesthe fluid channel 804 and the downspout 806. In a typical embodiment,the downspout 806 can be seen disposed within the fluid channel 804. Asshown in FIG. 9A, in certain embodiments, a single downspout 806 may beincluded in the fluid channel 804. However, as illustrated in FIG. 9B,in certain alternative embodiments, multiple downspouts 807(1)-807(5)may be included in the fluid channel 804. As previously illustrated inFIG. 4, thrust tabs (not explicitly shown in FIGS. 9A and 9B) may beincorporated with the plurality of apertures (not explicitly shown inFIGS. 9A and 9B) to direct the continuous-phase fluid 308 in a desireddirection thereby inducing the continuous-phase fluid 308 to cover theentire volumetric cross-flow area of a tray such as, for example, thetray 802(2). Additionally, at least one or a plurality of vanes 902 maybe incorporated to impart additional velocity to the continuous-phasefluid 308 and to further direct the continuous-phase fluid 308 to coverthe entire volumetric cross-flow window of a tray such as, for example,the tray 802(2). The vanes 902 may be curved, angled, or straight toreduce eddy currents in the continuous-phase fluid 308 and thedispersed-phase fluid 310 (not explicitly shown in FIG. 9).

It is thus believed that the operation and construction of the presentinvention will be apparent from the foregoing description. Although themethod and apparatus shown or described has been characterized as beingpreferred it will be obvious that various changes and modifications maybe made therein without departing from the spirit and scope of theinvention as defined in the following claims. For example, mostembodiments are described herein as having a heavier fluid in acontinuous phase; however, one skilled in the art will recognize that alighter fluid could comprise the continuous phase with minimal change tothe structure of the fluid-fluid exchange column. By way of furtherexample, the principles disclosed herein are applicable to various typesof separations trays including, for example, valve trays, sieve trays,and the like. Furthermore, the features discussed above with respect toFIGS. 1-9 may be combined and rearranged in numerous advantageous waysthat will be apparent to one of ordinary skill in the art. For example,although specific embodiments are discussed herein that have variousfeatures such as lighter fluid slots, ridges, and thrust tabs, it isfully contemplated that other advantageous embodiments may have anycombination of or even multiple instances of these features. Finally,specific embodiments are illustrated herein as pertaining to single-passtrays with a serpentine flow path; however, one skilled in the art willrecognize that the principles disclosed herein could be applicable toseparations trays having numerous types of flow paths including, forexample, dual-pass, multiple pass, orbital flow, and uni-directionalflow.

FIG. 10 is a is a diagrammatic, side-elevational, cross-sectional viewof a fluid-fluid exchange column according to an exemplary embodiment.In a typical embodiment, a fluid-fluid exchange column 1000 isconstructed similar to any of, for example, the fluid-fluid exchangecolumns 300, 500, or 800 shown in FIGS. 3, 5, and 8. In a typicalembodiment, a continuous-phase fluid 1008 is a light fluid and thusflows from a bottom portion to a top portion of the fluid-fluid exchangecolumn 1000. Likewise, a dispersed-phase fluid 1010 is a heavy fluid andthus flows from a top portion to a bottom portion of the fluid-fluidexchange column 1000. In a typical embodiment, during operation, thecontinuous-phase fluid 1008 moves across a tray such as, for example,the tray 1002(1), into a fluid channel 1004, and through at least one ofthe plurality of orifice constrictions 306(a)-306(c). As thecontinuous-phase fluid 1008 moves through at least one of the pluralityof orifice constrictions 306(a)-306(c), flow of the continuous-phasefluid 1008 is restricted resulting in increased velocity of thecontinuous-phase fluid 1008. The added velocity further facilitatesstirring and mixing of the continuous-phase fluid 1008 and thedispersed-phase fluid 1010 forcing the continuous-phase fluid 1008 to bespread entirely across a cross-flow volumetric window between successivetrays such as, for example, the trays 1002(1) and 1002(2) preventingstagnation and reducing recirculation (also referred to as “eddycurrent”) in the continuous-phase fluid 1008. Additionally, according toan exemplary embodiment, thrust tabs (not explicitly shown in FIG. 10)may be incorporated in conjunction with a plurality of apertures 1014 or1015 to direct the continuous-phase fluid 1008 to cover the entirevolumetric cross-flow window between each of the plurality of trays1002(1)-1002(5). FIG. 10 is included herein to demonstrate that either aheavier fluid or a lighter fluid may be used in operation as thecontinuous phase with appropriate modifications to a structure of thefluid-fluid exchange column.

Although various embodiments of the method and apparatus of the presentinvention have been illustrated in the accompanying Drawings anddescribed in the foregoing Detailed Description, it will be understoodthat the invention is not limited to the embodiments disclosed, but iscapable of numerous rearrangements, modifications and substitutionswithout departing from the spirit of the invention as set forth herein.

What is claimed is:
 1. A tray assembly for use in a fluid-fluid exchangecolumn, the tray assembly comprising: a plurality of trays, each of theplurality of trays comprising: a tray deck having a plurality ofapertures disposed therein; a fluid channel fluidly coupling at leasttwo trays of the plurality of trays; a diffuser skirt operativelycoupled to at least one tray of the plurality of trays, the diffuserskirt in fluid communication with the fluid channel and comprising aplurality of apertures; wherein the diffuser skirt distributes acontinuous phase fluid over substantially an entire surface of the traydeck; and wherein the diffuser skirt reduces recirculation of thecontinuous phase fluid.
 2. The tray assembly of claim 1 furthercomprising: a coalescing element disposed on a side of the tray deckfacing a flow of a dispersed phase fluid; and wherein the coalescingelement operable to promote coalescing of the dispersed phase fluid. 3.The tray assembly of claim 1 comprising a serpentine flow of thecontinuous phase fluid.
 4. The tray assembly of claim 1 comprising auni-directional flow of the continuous phase fluid.
 5. The tray assemblyof claim 1 comprising an orbital flow of the continuous phase fluid. 6.The tray assembly of claim 1, wherein the fluid channel is a downcomer.7. The tray assembly of claim 1, wherein the fluid channel is anupcomer.
 8. The tray assembly of claim 1 further comprising a pluralityof baffles disposed on the tray deck.
 9. The tray assembly of claim 8,wherein the plurality of baffles distribute the continuous phase fluidover a surface of the tray deck.
 10. The tray assembly of claim 1,wherein the plurality of trays are single-pass trays.
 11. The trayassembly of claim 1, wherein the plurality of trays are multi-passtrays.
 12. The tray assembly of claim 1, where in the plurality of trayscomprise multiple downspouts.
 13. A method of diffusing fluid phases ina fluid-fluid exchange column, the method comprising: providing afluid-fluid exchange column comprising: a plurality of trays; at leastone diffuser skirt operatively coupled to each of the plurality oftrays; flowing a first fluid across successive trays in a serpentineflow path; diffusing the first fluid through a diffuser skirt therebydistributing the continuous phase fluid over substantially an entiresurface of the tray; dispersing a second fluid within the first fluid;and flowing the second fluid through a plurality of apertures disposedin the plurality of trays.
 14. The method of claim 13 further comprisingdirecting the first fluid, via the diffuser skirt, in a desireddirection.
 15. The method of claim 13, wherein the first fluid is aheavy fluid and the second fluid is a light fluid.
 16. The method ofclaim 13, wherein the first fluid is a light fluid and the second fluidis a heavy fluid.
 17. A diffuser skirt for use in a fluid-fluid exchangecolumn having a plurality of trays associated therewith, the diffuserskirt comprising: a diffuser body having a plurality of aperturesdisposed therein; wherein the diffuser body is operatively coupled to atleast one of the plurality of trays; wherein the diffuser bodydistributes a continuous phase fluid over substantially an entiresurface of at least one of the plurality of trays; and wherein thediffuser body reduces recirculation of the continuous phase fluid. 18.The diffuser skirt of claim 17, wherein the diffuser body comprises aconduit.
 19. The diffuser skirt of claim 18, wherein the plurality ofapertures are disposed on both an interior face and an exterior face ofthe conduit.
 20. The diffuser skirt of claim 17, wherein the pluralityof apertures are grouped to create a desired flow pattern.
 21. Thediffuser skirt of claim 17, wherein the plurality of apertures compriseat least one of a slot, a louver, and a thrust tab.
 22. The diffuserskirt of claim 17, wherein the diffuser body is angled toward anexterior wall of the fluid-fluid exchange column.
 23. The diffuser skirtof claim 17, wherein the diffuser body comprises at least one of asemi-circular shape, a chevron shape, or a polygonal shape.